1. Technical Field
The present invention relates to image forming apparatus for forming a full-color image from toner images in different colors, and further to an image processing device to be mounted in such image forming apparatus.
2. Related Art
A lot of image forming apparatus for forming a full-color image from toner images in different colors has been widely known until now. As an example of the apparatus of such a type, there is image forming apparatus in which toner of a transparent color, or the so-called clear toner, is used for the purpose of enhancing e.g. glossiness and durability of printed images.
In order to present images in color of black, the image forming apparatus of such a type has often changed toner to use between black toner and process color black (PK) which is a colored toner mixture (superposing transfer composite) of cyan toner, magenta toner and yellow toner.
In such image forming apparatus, there are cases where black toner and clear toner are transferred to a transfer-receiving material, such as an intermediate transfer belt or a paper space, so that they are superposed upon each other at the surface of the transfer-receiving material. Such superposing transfer of black toner and clear toner has a problem that finally-obtained images tend to suffer the spreading of toner which is caused by toner scattering and referred to as blur. The blur of this type is conspicuous particularly in areas of small-width linear images, such as characters and drawings, and brings about degradation in image quality.